The transformers and reactors of power are equipments broadly used in systems of generation, transmission and distribution of electric power of average, high and extra-high tension.
These equipments generally use as insulating and of heat transfer ways, some kind of oil, which can be mineral, petroleum derivative, vegetable, silicone-based and so many another.
Such equipments are mounted in tanks and are provided of a nucleus, which constitute in magnetic plates, on which are mounted several coilings, such as primary, secondary and tertiary. The set nucleus more coilings is denominated active part, and works completely immersed in insulating oil, which should have its temperature supervised or monitored constantly, together with the temperature of the coilings.
Some transformers also have several intermediary derivations in their coilings, usually denominated “taps”, which allow the selection of the wished transformation relation between primary and secondary of the transformer, enabling thus the regulation of the exit tension of the transformer. The selection of tap to be used is made by a denominated equipment “Commuter of Derivations in Load” or “Commuter Under Load”, herein referred just as “commuter”, which is able to make tap change with the energized transformer and without interrupting the chain supply for the load. Also the commuter operates immersed in insulating oil, however in a compartment separated of the oil of the transformer in order to avoid the contamination of that, since in the tap change operations the contacts of the commuter interrupt electric arcs that deteriorate gradually the oil in which they are immersed.